Wireless multiple-input and multiple-output technology, as one of the key technologies to realize high-speed broadband wireless network access, can satisfy requirements for high transmission rate and extended coverage of future mobile communication, and is widely applied in mobile communication systems. With the development of the mobile terminal technology, the wireless multiple-input and multiple-output technology has increasingly complicated design environment, and is restricted by the appearance and size of the mobile terminal, especially hand-held mobile terminal, such that certain difficulties occur in multi-antenna implementation.
The design of current antennas often involves a need to provide a diversity antenna and a WIFI/BT/GPS antenna within a limited space. When a feed point of the diversity antenna is quite near to a feed point of other antenna, the two antennas will produce a coupling effect and thereby affect performance of the antennas. Therefore, isolation is a key indicator for judging magnitude of mutual influence between antennas. How to coordinate isolation between antenna units and limited size of a mobile terminal device to ensure excellent inter-antenna isolation within a working frequency band in limited environment is a main research issue of multiple antennas of the mobile terminal.